CREEP DEFORMATION MECHANISMS AND RELATED MICROSTUCTURE DEVELOPMENT OF AZ31 MAGNESIUM ALLOY

摘要

Because of ever increasing demanded of Magnesium alloys in various industries, high temperature deformation of Mg-Al-Zn alloys (AZ31) at constant stress (i.e. creep) were studied at a wide range of stresses and temperatures to characterize underlying deformation mechanism and dynamic recrystallization (DRX) Various microstructures (e.g. grain growth & DRX) are noted during steady-state creep mechanisms such as grain boundary sliding (GBS), dislocation glide creep (DGC) and dislocation climb creep (DCC). Although a combination of DRX and grain growth is characteristic of low stacking fault energy materials like Mg alloys at elevated temperatures, observation reveals grain growth at low strain-rates (GBS region) along with dynamic recovery (DRV) mechanism. Scanning Electron Microscopic (SEM) characterization of the fracture surface reveals more intergranular fracture for large grains (i.e. GBS region with DRV process) and more dimple shape fracture for small grains (i.e. DGC & DCC region with DRX).